The present invention relates to needle-bearing medical devices used, for example, to insert catheters into blood vessels of patients. More specifically, the invention relates to such a device having a retractable needle feature for rendering the device non-reusable and safely disposable.
Various types of medical devices employed a needle for piercing the skin of a patient for diagnostic or therapeutic purposes. One such device is an intravenous catheter insertion device for positioning a needle mounted catheter into a patient""s blood vessel. Once the catheter is properly positioned, the catheter insertion device is withdrawn leaving the catheter in place in the blood vessel. Handling of such medical devices after the needle is withdrawn from the patient can result in transmission of various pathogens, most notably human immune virus (HIV), due to in inadvertent needle stick to medical personnel.
Since the mid-1980s, concern over the risk of accidental needle stick injuries has spawned a number of design approaches for safety needle devices. Such devices can be broadly categorized as either sliding sheath needle devices, wherein a physical barrier is positioned over the needle tip after use or as devices with needle retraction, wherein the exposed portion of the needle is retracted into the device after use. The latter category of needle retraction devices can be further subdivided into manual and semiautomatic retraction devices. Manual retraction devices, as exemplified by U.S. Pat. Nos. 4,026,287 to Haller, U.S. Pat. No. 4,592,744, to Jagger, U.S. Pat. No. 4,808,169 to Haber and U.S. Pat. No. 5,067,490 to Haber, require the user to pull or slide a needle-connected mechanism rearwardly to retract the needle into the device. In semiautomatic needle retraction devices, a biasing member, such as a spring, may be employed to push or pull the needle into the device in response to activation by the user of a release mechanism. Such devices are exemplified by U.S. Pat. No. 4,813,426 to Haber et al. and U.S. Pat. No. 5,125,414 to Dysarz.
U.S. Pat. No. 4,747,831 of Kulli and U.S. Pat. No. 4,900,307 of Kulli show respective catheter insertion devices and syringes with semiautomatic needle retraction. The retraction mechanism shown in the last-mentioned two patents are disclosed to be actuable by the user upon depression of a release button after the catheter is removed from the insertion device or the needle is removed from the patient.
The prior art semiautomatic devices require manual actuation by the operator. In many situations, such as an emergency situation, the operator is distracted or rushed so that the manual step necessary to effectuate retraction is not performed, either intentionally or unintentionally. In such instances, the used needle remains exposed, creating a risk of an inadvertent needle stick. Therefore, it would be desirable to provide an automatic needle retraction mechanism in which needle retraction is effectuated by normal operation of inserting the catheter into the patient, without the need to perform a separate manual step. It is further desirable to provide a device with a limited number of components so that the device can be produced cost effectively.
With the foregoing in mind, the present invention provides a medical device having a hollow housing and a catheter mounted on the housing. The device includes a needle operable between an extended position extending forwardly from the housing and a retracted position in which the needle is enclosed in the housing. A biasing element biases the needle toward the retracted position. A needle retainer releasably retains the needle in the extended position against the bias on the biasing element. Preferably, the device includes a lock for releasably locking the catheter in an advanced position to hood the needle after the needle is inserted into the patient. Upon further advancement of the catheter relative to the device, the needle is released for retraction. The biasing element then propels the catheter rearwardly into the housing.
The present invention also provides a method for inserting a catheter into a patient using a needle-bearing medical device. The patient is pierced with the sharpened tip of the needle. The catheter is then advanced relative to the needle so that the catheter sheathes the sharpened tip of the needle. The catheter is then releasably locked in the advanced position to impede rearward displacement of the catheter relative to the needle. The advanced catheter is then advanced into the patient. After use, the needle is shielded so that the sharpened tip of the needle is protected against inadvertent contact. Preferably, the needle is shielded by retracting the needle automatically upon displacement of the catheter relative to the device.